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PANCREAS and ENZYMOLOGY in PEDIATRICS A. S. Senatorova, Y. V Omelchenko Kharkov National Medical University, Ukraine

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PANCREAS and ENZYMOLOGY in PEDIATRICS A. S. Senatorova, Y. V Omelchenko Kharkov National Medical University, Ukraine PANCREAS AND ENZYMOLOGY IN PEDIATRICS A. S. Senatorova, Y. V Omelchenko Kharkov National Medical University, Ukraine Key words: pancreas, pancreatic enzymes, exocrine secretion, replacement therapy, children Digestion is a single, integrated process because of the close linkages between different parts of the digestive tract. Impairment of the function of one of the gastrointestinal tract, usually leads to frustration in other organs. In different parts of the digestive tract occur various processes of absorption of nutrients. Important organ of the digestive system in the body is the pancreas. It is known that the pancreas is located in the retroperitoneal space, is the formation of length 14 −18 cm and a weight of about 85 −100. Under physiological conditions, the pancreas forms a day from 50 to 2500 ml of secretion. Pancreas performs two important functions in the body ― the endocrine (production of insulin and glucagon ― the main hormones that regulate carbohydrate metabolism) and exocrine (formation and deposition of various enzymes that hydrolyze nutrients). Enzymology history began in 1833, when A. Payen and J. Persaud established the role of diastase during fermentation of sugar into alcohol. Diastase got its name from the Greek word meaning "separation". For a long time diastase was called all enzymes (from Latin fermentum ― fermenting yeast). German physiologist V. Kuehne in 1878 suggested the name "enzyme" (from the Greek words en zimon ― "in leaven") not only for enzyme fermentation, but for all others, including enzymes and digestive system. As the detection of other catalysts of chemical processes in living systems at the suggestion of enzymes E. Duclos (1898) became known for hydrolyzable substrate by attaching the end -aza . At the end of the XIX ― the beginning of the XX century, it was found that enzymes exert their activity not only in living cells, but even after their destruction. Isolated, purified and crystallized enzymes from the pancreas of cattle began early last century. In clinical practice, the enzymes of plant, fungal and bacterial origin (solizim, Oraza) have some advantages over enzymes derived from the pancreas of pigs and cattle (acid resistance and relative cheapness). However, their lipolytic and amylolytic activity ten times weaker, and proteolytic ― no, that is responsible for their limited use. Pancreatic insufficiency limits food intake and leads to disruption of processes of absorption. Enzyme replacement therapy is the main focus in the treatment of patients with the syndrome of impaired digestion. Participation of the pancreas in digestion At receipt of food in the gastro-intestinal tract of the pancreas secretes into the small intestine the pancreatic enzymes and bicarbonates, neutralized with hydrochloric acid. List of key enzymes of pancreas and their involvement in digestion are shown in Table 1. Table 1 Digestive pancreatic enzymes Enzymes Secretion form Action Cleavage of polysaccharides into α-amylase Active maltose and maltotriose Hydrolysis of triglycerides to form lipase Active fatty acids and monoglycerides Hydrolysis of phosphatidylcholine to phospholipase А The proenzyme is activated by trypsin produce fatty acids lizofosfatilholin Hydrolysis of cholesterol esters and Карбоксилэстераза Active esters of fat soluble vitamins The proenzyme is activated with Cleaves proteins and polypeptides trypsin enterokinase within the protein molecule Protein cleaves internal connections chymotrypsin The proenzyme is activated by trypsin in the area of aromatic amino acids, leucine, methionine, glutamine elastase Proelastase activated with trypsin Cleaves elastin, a protein of connective tissue Cleaves a peptide bond to the Carboxypeptidase А and В Proenzyme activated by trypsin carboxyl terminus of aromatic (A) and base (B) amino acid residues Basic hydrolytic processes occur in the small intestine where nutrients are broken down into monomers are absorbed and enter the blood and lymph. The processing of nutrients in the small intestine takes place in three successive interconnected stages: • cavitary digestion; • membrane digestion; • absorption. Enzymes hydrolyzing fats and carbohydrates (α-amylase, lipase) are secreted in an active state, proteolytic enzymes (trypsin, chymotrypsin, elastase, carboxypeptidase) ― as zymogens that are activated in the lumen of the small intestine. Intestinal enzyme places an important role in their activation ― enterokinase, which transmits trypsinogen to active trypsin. Trypsin, in turn, activates the proteolytic enzymes remaining. During cavitary digestion carbohydrates (starch, glycogen) to split pancreatic amylase disaccharides and small amounts of glucose. Under the action of proteolytic enzymes produced low molecular weight peptides and small amounts of glucose. Fats in the presence of bile pancreatic lipase to hydrolyze the di-and monoglycerides, fatty acids and glycerol. Lipase most rapidly loses its activity, and in the ileum normally determined only by an insignificant amount. Proteases, particularly amylase, are more stable and retain, respectively 30 and 45% of its activity in the terminal small intestine. The basis of reduction of lipase activity is under the influence of its proteolysis and proteases, especially chymotrypsin. Uneven enzyme activity from the proximal to the distal small intestine observed in healthy individuals and, particularly, those with exocrine pancreatic insufficiency. This explains the fact that develops much earlier violation fat digestion than starch or protein. Causes of digestive disorders Exocrine pancreas dysfunction occurs in various diseases. Pancreatic dysfunction due to developing: • maldigestion ― maldigestion (splitting) of food polymers (proteins, fats, carbohydrates) to the suction necessary for the components (monoglycerides, fatty acids, amino acids, monosaccharides); • malabsorption ― malabsorption of nutrients, leading to an eating disorder patient expressed. The main causes of indigestion, malabsorption and maldigestion accompanied by children are the following: Insufficiency of cavitary digestion: • pancreatogenic internal secretorial insufficiency (chronic pancreatitis, pancreas stones, subtotal pancreatectomy, pancreas cancer, pancreas fistula, cystic fibrosis, malignant malnutrition); • reduction in the activity of enterokinase and inactivation of pancreatic enzymes in the gut (Zollinger-Ellison syndrome, duodenal ulcer, duodenitis, intestinal dysbiosis); • violation of the transit of intestinal contents and violation mixing enzymes with food chyme (duodeno-and gastrostasis, irritable bowel syndrome, post- vagotomy and drainage operations); • reduction in the concentration of enzymes as a result of dilution (post gastrectomy syndrome, intestinal dysbiosis, a condition after cholecystectomy); • violation of products cholecystokinin, pancreozymin, secretin deficiency of bile acids in the small intestine, congenital or acquired (biliary obstruction, severe hepatitis, primary biliary cirrhosis, the pathology of the terminal small intestine, small intestine dysbiosis, cholestyramine treatment); • gastrogene failure (gastrectomy, gastrectomy, atrophic gastritis). Violation of membrane digestion ― congenital or acquired disaccharidase lactase or other failure, the intracellular transport of food components as a result of the death of enterocytes (Crohn's disease, gluten enteropathy, sarcoidosis, radiation, and other ischemic enteritis). Violation of the outflow of lymph from the intestine ― obstruction of lymphatic ducts (limphoangectaziya, lymphoma, tuberculosis, cancer, carcinoid). Combined disturbance (diabetes, giardiasis, hyperthyroidism, hypogammaglobulinemia, amyloidosis, AIDS). It is recalled that in practice is more common secondary or relative, pancreatic insufficiency is usually caused by taking an unusual food, its excess amount or inflammatory diseases of the upper digestive canal. The latter is associated with the development of secondary mechanisms relative exocrine pancreatic insufficiency. Exocrine pancreatic insufficiency is based on the following mechanisms (Alexandr Yakovenko, 1998, with modifications): • pancreatic immaturity; • destruction of acinar cells (decreased synthesis of enzymes); • obstruction of the pancreatic duct, pancreatic juice flow violating the duodenum; • reduced secretion of bicarbonate ductal epithelium of pancreas, leading to acidification of the duodenal contents to pH 4.0 and lower, resulting in denaturation of pancreatic enzymes and bile acid precipitation; • failure due to lack of activation of enzymes and bile enterokinase; • dyskinesia duodenum and small intestine, so that there is a violation of mixing enzymes with food chyme; • violation of intestinal microbiocenosis (inactivation of enzymes and destruction), hypoalbuminemia due to lack of protein in the diet (violation of enzyme synthesis). Clinical signs of exocrine pancreatic insufficiency It is now well known clinical signs of severe pancreatic insufficiency. Appears badly digested bowel movement of fatty nature, often gray in color, with a sharp unpleasant odor. Patients complain of flatulence, often pain, flatulence, loose stools. Body weight is reduced, sometimes at a quite good appetite. Symptoms of vitamin deficiency due to reduced revenues fat-soluble vitamins (A, D, E, K). With all the variety of diseases involving pancreatic insufficiency, the task of the physician is to spending a differential diagnosis, to establish the cause and correction in a timely manner. To clarify the diagnosis
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